TP53 and neoplasm: Because of the lower difference in radiation sensitivity among cell cycles and a lesser capacity for PLDR and SLD repair when carbon-ion beams, especially high LET beams, were used, the RBE values in Q tumor cells 9 h after HDRI and immediately after RDRI were relatively larger than those immediately after HDRI (Table 4), irrespective of p53 status of tumor cells.